SPF Record Checker
Lookup and validate your SPF record.
What is SPF Record?
SPF (Sender Policy Framework) is an email authentication protocol that allows recipients to distinguish between the domain owner’s authorized list of senders, and unauthorized emails. Authenticating your email using SPF is the first step toward preventing domain name abuse and impersonation. To configure SPF you have to set up a DNS record. Pairing your SPF record with other email authentication DNS records can increase its efficacy against cyberattacks.
Our SPF checker is a software tool that helps you look up and check for errors in your SPF record. SPF checks help you to verify your domain’s SPF (Sender Policy Framework) configuration.
SPF Record Examples
1. Basic SPF record: v=spf1 mx -all
Explanation:
mx: Allows all the mail servers listed in the domain’s MX records to send email.
2. SPF record allowing specific IP addresses: v=spf1 ip4:192.0.2.1 -all
Explanation:
ip4:192.0.2.1: Allows the server with the IP address 192.0.2.1 to send email.
ip4:198.51.100.1: Allows the server with the IP address 198.51.100.1 to send email.
3. SPF record including another domain’s SPF record: v=spf1 include:_spf.example.com -all
Explanation:
include:_spf.example.com: Includes the SPF record of example.com. This means any servers authorized to send mail for example.com are also authorized for this domain.
SPF Record Tags Explained
SPF records are published in DNS (Domain Name System) and are comprised of several tags that define the syntax of the record. Here’s a breakdown of the commonly used SPF tags:
- v: This tag specifies the version of SPF being used. For SPF version 1, the value is “spf1”.
- mx: This tag allows the domain owner to designate the domain’s MX (Mail Exchanger) servers as authorized senders. If the sending server matches one of the MX records for the domain, it is considered legitimate. Default value: current domain.
- a: This tag permits the sender to verify the IP address of the sender’s domain name. Default value: current domain.
- ptr: This tag checks if the reverse DNS (PTR) record of the sending server resolves back to the original domain name. It’s not commonly used or recommended as it is unreliable, slow, and places load on .arpa name servers (ref: RFC document)
- IP4/IP6: This tag specifies the authorized IPv4 and IPv6 addresses that are allowed to send emails on behalf of the sender’s domain.
- include: This tag allows the inclusion of SPF records from another domain. This is useful for domains that use third-party email services, as they can include the SPF records of those services in their own SPF record.
- all: This tag specifies the default action for emails that do not match any of the preceding mechanisms. It can have 4 possible values: +, ~, -, ? and it is a mandatory tag that is placed at the end of every SPF record.
- Here’s an example of an SPF record:
- v=spf1 include:_spf.example.com mx -all
- In this example:
- v=spf1 indicates SPF version 1.
- include:_spf.example.com includes SPF records from _spf.example.com.
- mx permits the domain’s MX servers to send email.
- -all specifies that any emails not matching the authorized senders should be rejected.
Why You Need to Test SPF Record?
An SPF checker tool can reduce the chances of your legitimate email messages landing in the spam folder, improve your overall email security, and filter out fraudulent emails. Here are the various benefits of frequent SPF record checks:
Verify the authenticity of email communications
Ensure that your record stays under the DNS lookup limit
Comply with Google’s latest bulk email senders’ requirements
Bypass spam filters more easily
Drive dot-com e-services
Detect syntactical errors with this SPF diagnostic tool
Authorize the range of IP addresses for your legitimate sources, email clients, email service providers, and third-party email service providers
Common SPF Configuration Mistakes
SPF (Sender Policy Framework) is a powerful email authentication method to prevent email fraud. However, domain owners often make mistakes during the configuration process that can undermine its effectiveness. Here are some common errors to avoid:
- Misalignment with Third-Party Vendors: Domain owners do not align their sending sources for third-party email vendors by following the sender alignment guidelines of their domain registrar
- Invalid or Broken SPF Records: Non-authorized sources get a free pass to send emails from your domain due to invalid or broken SPF records
- Lack of Complementary Protocols: Senders do not set up complementary email authentication protocols like DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication Reporting and Conformance) to improve their domain’s security further
- Ignoring Best Practices: Senders fail to follow optimal email deliverability practices recommended by email experts and instead rely only on traditional anti-spam filters and built-in email gateways
How to Make Sure Your SPF Record is Valid?
- Instead of relying on DIY methods that are prone to human errors, use an SPF record generator tool to create your record automatically.
- List down all your sending sources to add as authorized senders in your SPF record. Make sure you are updating this list from time to time to remove any redundant IP addresses or includes that can add more lookups.
- Use a hosted SPF service that will make SPF record management easier. This will allow you to monitor and remove netblocks, keep track of your included domains, and comply with SPF limits.
- Make sure your SPF record does not exceed the 10 DNS lookup limit. This can be achieved with the help of an SPF flattening service or SPF macros – though we recommend the latter.
- Avoid using the SPF PTR mechanism. As PTR records resolve an IP address to a domain name, it slows down the DNS lookup process. It is also considered to be highly unreliable as per section 5.5 of RFC 7208.
- Make sure you are only publishing 1 SPF record per domain. Publishing multiple SPF records can invalidate your SPF configuration.
More Email Authentication Protocols to Explore
- DKIM
- If you want to ensure your messages cannot be tampered with before they are delivered, DKIM can help! DKIM one-ups SPF by even surviving email forwarding scenarios.
- DMARC
- If you want to stop an authorized or suspicious email from being delivered to your client, a DMARC policy can help. This domain-based message authentication protocol allows you to define delivery policies for emails that fail authentication, along with reporting capabilities.
- BIMI
- Visual logos are the thing of the future! BIMI helps you display your brand logo in your receiver’s inbox which gives a professional look and feel to your emails. It also increases brand recall and promotes trust.
- MTA-STS
- MTA-STS helps you as an email receiver, combat man-in-the-middle attacks. It forces messages to get transmitted over a TLS-encrypted SMTP channel, to prevent attackers in the middle from tampering with the connection or reading your emails.
SPF Record Check FAQs
Check our comprehensive database of popular SPF record checker questions we come across often on our support forum.
With PowerDMARC, SPF record checks are completely free of charge no matter how many times you need to check SPF compliances and for how many different domains. However, lookups are performed 1 domain at a time.
Our email authentication experts recommend domain owners to perform SPF checks once every month to ensure that record validity is maintained.
You need SPF to enhance email security and prevent email spoofing as it allows receiving mail servers to check whether the incoming email is sent from an authorized source.
Along with SPF, it is important to set up DMARC and DKIM for well-rounded protection against cyber attacks and reduce your DNS lookups with an SPF flattening tool.
To check the SPF record in Office 365, follow these steps:
- Log in to your Office 365 Admin Center
- Go to Settings > Domain
- Select your domain name and click on DNS records
- Check if your TXT status is ok, and review your SPF record from the list of DNS records.
Failing SPF checks in email authentication can lead to several consequences:
- Increased likelihood of emails being marked as spam or rejected by recipient servers.
- Diminished email deliverability, affecting communication with clients, partners, or customers.
- Higher risk of phishing attacks succeeding, as spoofed emails may appear legitimate to recipients.
- Damage to sender reputation, potentially leading to being blacklisted by email service providers.
- Negative impact on brand reputation due to compromised email security and potential misuse of the sender’s domain.
At ExpertDMARC, we do more than just offer SPF flattening services. While our platform fully supports automatic and dynamic flattening methods for SPF, we also offer an alternative (and better) solution. In several cases, traditional as well as automatic SPF flatttening methods fall short in optimizing your record effectively. Hence, we encourage using Macros.
Our platform supports SPF Macros integration which optimizes your record to stay under SPF limits for both lookups and character length! Macros is also effective in far more complex situations incomparison to flattening. This ensures an optimal and error-free SPF experience.
It's recommended to periodically monitor and maintain SPF records for your domain, especially after any changes to your email infrastructure or domain settings.
A good practice is to check SPF records whenever you make updates to your DNS records, email servers, or sender policies. Additionally, regular checks, such as every few months or after significant changes, can help ensure the continued effectiveness of your SPF configuration.
If the SPF checker tool identifies errors or inconsistencies in your SPF records, consider the following steps:
- Review the SPF record syntax and configuration for accuracy, ensuring that it includes all authorized email sources.
- Correct any misconfigurations, such as missing or incorrect IP addresses, or mechanisms.
- Update DNS records with the revised SPF information and allow time for DNS propagation.
- Test the revised SPF record using the SPF checker tool to verify its accuracy.
- Monitor email deliverability and SPF authentication status to ensure that the issues have been resolved effectively through DMARC reports.
- Consider consulting with our email security experts for assistance in troubleshooting and optimizing SPF configurations. Contact us now!
To help keep your SPF record functioning properly, you can following the tips given below:
- Make sure you are following RFC-specified SPF restrictions. The details of these limitations have been explained more in the next question.
- Make sure you are authorizing all your email sending sources, including third party vendors. Failing to authorize email vendors and service providers you use to frequently send emails can lead to serious deliverability issues. Generally, you can find configuration guides in the support section in each of your vendor websites. Alternatively you can check out our FAQs and blogs to find steps to configure SPF records for most vendors.
- Avoid using SPF mechanisms like the “PTR”. It is widely considered as unreliable and slows down the authentication process. It also introduces more complexities in your SPF record.
- White SPF “-all” and “~all” can both be configured as a part of best SPF practices, in case of safe SMTP relaying we recommend using the softfail mechanism (~all). On a hardfail policy, relayed SMTP emails will fail SPF, leading to potential deliverability issues.
There are several reasons why SPF record optimization may come in handy. Given below are some of the reasons:
Outdated SPF records
Your SPF record may be outdated. In the sense, you may have expanded your emailing efforts by onboarding other email service providers or simply switched from your current vendor to a new one. Your DNS doesn’t know this! Hence you need to access your DNS to edit your SPF record and include these new sending sources.
Extremely long SPF records
If your SPF record is too long, so much so that it exceeds the string character limit, then optimization becomes important. You need to shorten your record to stay under the character length limit so SPF functions properly.
SPF records requiring more than 10 lookups
Often times your SPF record may need more than 10 DNS queries to lookup and verify sending sources. This isn’t permitted and can lead to SPF permerror. Hence you may need to optimize your record to reduce complexities and stay under the permitted lookup limit.
The Internet Emgineering Task Force defines a set limit for the number of permitted lookups during an SPF verfication session. The maximum number is 10. If an SPF record exceeds 10 DNS lookups, SPF breaks and returns a permerror result.
Moreover, IETF also limits the number of void lookups (DNS lookups which return an empty response) to a maximum of 2.
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